1. Field of the Invention
The present invention relates to a detachable casing that can be adapted to a mouse type peripheral for a computer. This casing comprises input commands designed to be added to the commands of a standard computer peripheral and to control the representation of a third dimension on a computer screen.
2. Description of the Prior Art
Many devices capable of simulating a third dimension have already been devised. Thus, initially, devices distinct from computer peripherals comprising one or more pressure sensors were made. These devices are described especially in the patent application EP-A-0 330 270 and take the form of pedals that can be activated by foot or packs that can be activated by hand. The pressure sensors react to the pressure of the foot or to a user's fingers and convey information in a third dimension to a computer. Such devices are used only to control the representation of an effect of perspective; they do not affect the representation of the first and second dimensions. Their use therefore necessarily implies the concomitant handling of a standard peripheral for computers. Now, since the two distinct devices cannot be handled by only one hand, it becomes difficult to simultaneously activate several input commands. Consequently, these devices are not ergonomical.
To overcome this ergonomical problem, one solution consists in adding pressure sensors, capable of reacting to the pressure of an operator's fingers or hand, directly to computer mouse type peripherals. These peripherals can therefore be used both to plot a line in two dimensions using standard x-axis and y-axis positioning commands and to simulate a third dimension by obtaining a variation in the thickness of the line by means of the pressure sensors. Such computer peripherals are described especially in the French patent application FR 95 044015, the patent application WO-A-88 8565 and in an article entitled "Depth/Force Capability for Mouse Painting Devices" in the journal Research Disclosure No. 342, October 1992, page 769. These devices however require a conversion of the standard peripheral, which therefore leads to a considerable increase in its manufacturing cost.